1. Heat up a frying pan.   

2. In the heated frying pan, place the slices of bacon in the pan. Cook the bacon slowly over medium low fire to render all the fat and make it crispy. As it cooks, remove the fat that the bacon is losing with a spoon and put it aside in a small container. Do not throw the fat out!

3. In another frying pan, add the fat from the bacon and heat over medium fire. Pad the burger patties dry with a paper towel and season both sides of the patty with salt and pepper.

4. When the fat starts to smoke, gently place the burger patties in the pan and cook the burger patties for about 4 to 5 minutes.

5. Flip the burger and place a slice of Manchego cheese on top to have it start melting. On the last two or three minutes of the cooking process, add about 15 grs of cold unsalted butter to the pan and let it foam. Baste the burger pattie for two more minutes. Remove from the pan and set aside.

6. Spread a dollop of soft unsalted butter on both sides of the burger buns and in another pan, heat them over medium low fire until golden brown on both sides.

7. Assemble the burger placing the cooked burger patty on the bun, topping with two slices of the crispy bacon, lettuce, a tomato slice and some onion rings.

8. Enjoy!